The ghost of the 2024 election continues to haunt Kamala Harris as she revisits her ill-fated decision to put Tim Walz on the ticket. Harris writes in her new memoir that the Minnesota governor was not her “first choice” for vice president, despite the enthusiasm she showed Walz in the days after he was suddenly announced. Many observers speculated that the Democrats’ No. 2 slot became a contest between Walz and Pennsylvania Gov. Josh Shapiro, who Harris aides feared would provoke a backlash among pro-Palestinian progressive activists because he is Jewish. But in “107 Days,” the former vice president writes...